/****************************************************************************
 *
 *  Copyright (c) 2017, Michael Becker (michael.f.becker@gmail.com)
 *
 *  This file is part of the FreeRTOS Add-ons project.
 *
 *  Source Code:
 *  https://github.com/michaelbecker/freertos-addons
 *
 *  Project Page:
 *  http://michaelbecker.github.io/freertos-addons/
 *
 *  On-line Documentation:
 *  http://michaelbecker.github.io/freertos-addons/docs/html/index.html
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files
 *  (the "Software"), to deal in the Software without restriction, including
 *  without limitation the rights to use, copy, modify, merge, publish,
 *  distribute, sublicense, and/or sell copies of the Software, and to
 *  permit persons to whom the Software is furnished to do so,subject to the
 *  following conditions:
 *
 *  + The above copyright notice and this permission notice shall be included
 *    in all copies or substantial portions of the Software.
 *  + Credit is appreciated, but not required, if you find this project
 *    useful enough to include in your application, product, device, etc.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 *  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 *  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 *  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 *  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 *  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 ***************************************************************************/


#ifndef READ_WRITE_LOCK_H_
#define READ_WRITE_LOCK_H_


/**
 *  Handle for Reader/Writer locks.
 */
typedef void * ReadWriteLock_t;


/**
 *  Create a Reader/Writer lock that offers preference 
 *  to all readers.
 *
 *  @return A handle to the lock, or NULL on failure.
 */
ReadWriteLock_t *CreateReadWriteLockPreferReader(void);


/**
 *  Create a Reader/Writer lock that offers preference 
 *  to all writers.
 *
 *  @return A handle to the lock, or NULL on failure.
 */
ReadWriteLock_t *CreateReadWriteLockPreferWriter(void);


/**
 *  Free an already allocated Reader/Writer lock.
 *
 *  @param lock The lock you are freeing.
 */
void FreeReadWriteLock(ReadWriteLock_t *lock);


/**
 *  Lock as a Reader.
 *
 *  This allows you shared read only access to whatever is being 
 *  protected by this lock.
 *
 *  @param Lock The lock you are taking.
 */
void ReaderLock(ReadWriteLock_t *Lock);

/**
 *  Unlock as a Reader. 
 *
 *  You should have already locked this using ReaderLock().
 *
 *  @param Lock The lock you are releasing.
 */
void ReaderUnlock(ReadWriteLock_t *Lock);

/**
 *  Lock as a Writer.
 *
 *  This allows you exclusive read / write access to whatever is being
 *  protected by this lock.
 *
 *  @param Lock The lock you are taking.
 */
void WriterLock(ReadWriteLock_t *Lock);

/**
 *  Unlock as a Writer. 
 *
 *  You should have already locked this using WriterLock().
 *
 *  @param Lock The lock you are releasing.
 */
void WriterUnlock(ReadWriteLock_t *Lock);


#endif

